Objective: To obtain additional information on the relation between charged groups on the cell surface and the immunological properties of the cell in order to shed light on the relationship between surface charge, immunogenicity and malignancy and to study the role of enzymes, particularly neuraminidase, in modifying the immune response to malignant cells. Approach: A comparative electrophoretic and immunological study of human blood cells. Cells will be studied in the sequence 1) erythrocytes, 2) normal lymphocytes, 3) leukemic lymphocytes and lymphoblasts, 4) granulocytes, and 5) monocytes and macrophages both before and after treatment of the cell surface by neuraminidase, trypsin and other enzymes. A streak deflection method of electrophoresis will be used to measure mobilities. Erythrocyte surface antigens will be determined by standard serological methods and lymphocyte typing and determination of immunological reactivity against leukemic cells will be by cytotoxity and mixed leukocyte culture methods.